Recently noticed an interesting feature on a card I had previously used for NOOBS, had formatted using SDFormatter and then copied a new OS onto (Openelec).

The card, when in windows, showed only one partition of the right size. When on the Pi however there was a slightly random 27Mb partition (mmcblk0p3 I think) which contained NOOBS files (presumably for recovery purposes?). Is this meant to happen after using SDFormatter to clear a NOOBS disk?

If you used SDFormatter properly it would have left a single partition on the card. You don't say how OpenELEC was then put on the card but you should not then be able to see any NOOBS files on the card.

I agree, thats what should happen. I used SD formatter using the standard instructions, copied the Openelec files on (i.e. didn't do a NOOBS openelec install as in that case I'd expect to see the extra partition.

Also, its not just windows - mini partition tool didn't notice it, even using ext2fs to see ext2/3/4 FSs didn't recognise it